SINCE the publication of my article on "Physiology of Mind-Reading," in the February number of your Monthly, I have received the following, which, as presenting a new phase of the subject, is of much interest.

There are three general methods of mind-reading—by the touch, by the eye, and by the ear. My article was devoted only to the method and modifications of the method introduced by Brown—by the touch. Mind-reading by the eye—that is, watching the movements and changes of the features, or of the hand or fingers—is done every day by all of us, and is frequently utilized with great success by mediums. Mind-reading by the ear, as described in the first experiment noted in the following letter, is not so well known. The author of the letter, who does not wish to have his name used, is also an expert in the art of mind-reading by the eye or by the touch.

The general physiological principle is the same in all these methods of mind-reading—namely, the detecting by the operator, through some one of the senses, of the unconscious muscular or bodily movements of the subject, through mind acting on body.⁠George M. Beard, M.D.

Dr. George M. Beard—

Dear Sir: I was much interested in your article on the "Physiology of Mind-Reading," as I have paid more or less attention to the subject, in an amateur way, for eight or ten years past, and I think that I can give you some new "developments."

While your theory is undoubtedly correct, you describe certain conditions as "essential" which I have found by frequent successful practice to be unnecessary. Thus you say that the connection between the subject or subjects must be such "as easily to allow the sense of muscular tension to be communicated." The operator or medium "must be in physical connection with the subject." Again, "where the connection of the operator with the subject is made by a wire, so arranged that mass-motion cannot be communicated, . . . the operator does just what he would do by pure chance and no more." In reply to this, I would say that I am in the habit of repeating Brown's tricks of finding hidden objects, designating persons and things thought of, etc., without any physical contact whatever, while I am blindfolded, precisely as Brown was in his public performances.

The only condition I require of the subject is, that he shall follow me at a distance of about three or four feet, as I grope my way apparently at random, keeping his mind fixed upon the object. I am able to tell, by close attention, when he follows me readily, and when reluctantly; in this way I cautiously map out the direction in which he tends to follow me most readily. When I approach the vicinity of the object thought of, he shows no inclination to move in any one direction. There is, of course, a certain element of uncertainty in the finding of a small object under these circumstances, but the proportion of failures is astonishingly small. I reached this result by a succession of experiments, first through a rigid rod, then through a wire, then a stretched string, then a string with a loop. I then worked without contact not blind-folded. I would walk backward, holding out my right forefinger, and directing the "subject" to hold his right forefinger, at a distance of six inches (this would convey to most people the impression of two terminal poles of a battery or electrical machine), and he would often have an imaginary pricking, as of sparks at the finger-tip. I would then proceed around the room, and when moving in the right direction the hiatus would be rapidly closed between the two fingers.

I can almost invariably distinguish an intentional or accidental indication from an involuntary one, and I do not find that keeping the "arm perfectly stiff" interferes very seriously. The indications are not confined to muscular contractions or relaxations of the arm, but it is a sympathetic movement of the whole body.

It is a curious fact that subjects who naturally work well will be very slightly influenced by the explanation of the apparent mystery. You may assure them that every correct movement you make is only a translation of their own, and they will declare positively that they are trying to move in the opposite direction, and, in fact, they often do hold back with their feet, while giving the most positive indications with their arms.

I have found that a large majority of well-educated people have an innate bias for mysteries, and prefer to refer these "phenomena" to animal magnetism, auras, psychic or odic force, or any incomprehensible cause, rather than to the rational explanation of unconscious movement. Some time since, I had a curious illustration of this fact, and at the same time an admirable proof of the physical theory (if any were required), in an experiment suggested by a gentleman of this city. I had concluded a successful exhibition at an evening company, and described the precise method by which the experiments had been performed. This gentleman said to me privately that he could suggest an experiment which, if successful, would disprove my theory of muscular or physical movement. I retired from the room, and was brought in blindfolded. Meanwhile he had requested a very good subject with whom I had done a number of complicated things to hide an article. The gentleman then took the towel from my head and blindfolded the "subject"—turned him rapidly round several times, and told him to think of the object. He said, "Now you will find it by mental communication only." I started off rapidly, but, of course, received no indications. I then purposely touched his hand to the mantel-piece in the back-parlor. Instantly he unconsciously calculated the position of the hidden article and directed (not led, for I always go in advance of the "subject") me toward the front-room; then he was lost, until I again touched his hand to some object, when I received a fresh indication. In this way I finally found a ten-cent note, rolled into a little ball, and attached to the lower knot of a cord running through the handle of a small feather-duster, which was hanging from the bell-handle on the wall. I did not, however, immediately produce it, as I wished to experiment further. I led the "subject" off to another part of the room, and he immediately brought me back to the duster. Again I led him away to the same place, and turned him round so as to confuse him. All indications ceased, even when I held his hand within an inch of the duster.

In regard to finding small objects, I have no difficulty in picking out any letter on a page of a book or newspaper, and I frequently spell out abstract thoughts or names of people, places, etc., thought of, in this way: I hold a sharp-pointed stick or pen-handle in my left hand, pointing downward, with the same hand grasping the left hand of the "subject." I thus pick out letters on the page which spell the thought in the mind of the "subject."

The power of perception of these minute indications is capable of being developed to an astonishing degree, and I have often been amazed at the curious effects produced, a few of which I have indicated to you.

To the Editor of the Popular Science Monthly.

In Tyndall's discourse on "Fermentation and its Bearings on the Phenomena of Disease," as published in the December number of The Popular Science Monthly, he describes an injury he met with in falling upon some sharp rocks. He limped to his hotel, and remained quietly in bed for four or five days, and, having quite recovered, removed the bandages, and found the wound "perfectly clean, uninflamed, and entirely free from pus." This slight exposure led to inflammation, an accumulation of pus, and, finally, to an abscess several inches below the wound, and might have led to fatal results. A year after, Tyndall exposed in the same room tubes containing organic infusions, and in two days the infusions were swarming with the bacteria of putrefaction with which the dust-laden atmosphere was charged.

I have lately been reading General Hazen's interesting book entitled "The School and the Army," and in it find the following testimony regarding the treatment of wounds in in-door and out-door hospitals, which, taken in connection with Dr. Canniff's correspondence in the April number of your magazine concerning Dr. Lister's antiseptic treatment of wounds, may be of interest to your readers. General Hazen says:

"The Germans have fallen into the same error that we committed—that of using buildings for hospitals instead of tents, or field-hospitals; and there is scarcely a doubt that the French will do likewise. It is unaccountable that scientific and practical medical men do not appreciate and advocate the advantages of out-door over in-door hospitals. It is a matter of the gravest importance, and the humane societies of Christendom can in no way do more good than by thoroughly investigating and making generally known the facts relating to permanent hospitals in time of war. The seeds of disease cling to the walls, ceilings, and floors, and the death-rate of the wounded is often greatly increased by putting them in these places. So strongly was I impressed with this in our war that, as far as was in my power, I kept my wounded out of them. At the battle of Mission Ridge, the colonel of the Forty-first Ohio lost his leg above the knee by a musket-shot I forbade his going to hospital, and caused him to be treated in his rude, split-shingle cabin, and his recovery was remarkably rapid. Officers of my command who were grazed by musket-shot upon the arms were put into the hospital, and died from gangrene. At that battle the wounded of General Thomas's army were treated in fixed hospitals, or buildings fitted up beforehand at Chattanooga, with many comforts and good care. The proportion of deaths among the wounded was frightful; and we were told that it was due to the low vital condition of our men, resulting from short rations. The fact was, they died from hospital diseases. General Sherman's army, just arrived from Mississippi, without hospitals, treated their wounded in the field, and the proportion of recoveries was astonishingly great. They were cured by fresh air. At the battle of Peach-Tree Creek, a very worthy staff-officer of mine was seriously, although not dangerously, wounded in the abdomen. The medical rules were very strict, but, by sending messengers all night, I got authority to send him home to the North, without his going to the hospital. Arriving at Nashville, and being unable to proceed without further medical authority, he was taken charge of, and put into one of their comfortable hospitals. In a few days he became terribly afflicted with gangrene, and only escaped with his life after a perilous and racking illness."

These observations are doubtless familiar to surgeons; but if, with Tyndall's experiments, they are found to be absolutely correct, does it not become necessary to examine into the condition of the various hospitals throughout the country, and to provide at least some special conditions for the treatment of flesh-wounds—an apartment, for example, separated from the main building, which may be deluged at intervals with superheated steam to destroy the germs, or such other precaution as shall insure an atmosphere of absolute purity during the dressing of wounds?

We would commend this subject to the State Boards of Health.

Edward S. Morse.⁠

⁠Salem, Massachusetts,April 26, 1877.

THE NEW IDEAS ABOUT SPACE.

To the Editor of the Popular Science Monthly.

The great attention now given to this subject in Europe seems to render appropriate a short communication to bring it more directly before Americans. In point of fact, the mathematicians have been making a conquering migration into the fair fields of philosophy, and instead of any longer being content to receive from Metaphysics her definitions of space, they have for themselves attacked the question by the methods furnished by two thousand years of advance in their own science. Already they have made some wonderful strides toward the solution, and the new notions are very fascinating.

It is, perhaps, daring to attempt to give an adequate idea of some of these without the use of mathematical symbols and analytic geometry; still it seems desirable for each of the special sciences to be able to express results in untechnical language, and we will try.

Every schoolboy knows that what is called multiplying a linear inch by a linear inch gives a square inch, and that again multiplying this square inch by a linear inch gives a cubic inch. Now, I suppose, many of the most original boys may have asked themselves, "What would be the result of multiplying this cubic inch again by a linear inch?" Up to this nineteenth century the answer has probably always been, that the thing was unthinkable and inexpressible, and that, although by analogy we see no reason for being stopped so abruptly, yet such is our invariable experience.

Now, the two men who first and independently stepped over this mental fence were the great Gauss whom Germany is now celebrating, and a Russian named Lobatchewsky. They both said that the space with which we are familiar is only one kind of space out of a number of possible spaces, each logically self-consistent; but that, from the fact of all our ages of experience being in this particular space, we cannot perfectly picture to ourselves any one of the other kinds, though they are entirely expressible in analytic geometry.

Now, it has often been remarked that in things very familiar to us we see nothing noteworthy. So we see nothing strange in our conception of a straight line and a plane, yet we may think it strange when we are told that this peculiar notion of straightness, smoothness, or flatness, is also inherent in our ideas of our space. This was discovered many years ago by Prof Sylvester, and, to denote it, he called our space a homaloid, or a homaloidal space. To us it always has three dimensions, and no more; and, just here, all readers may be advised not to try to picture to themselves any higher kind of space, since they must fail as utterly as they fail to see the ultra-violet rays of the spectrum. Moreover, it has not yet been demonstrated that any other kind of space actually exists in the physical world. This is a matter which can only be settled by physical experiments; and perhaps it is to be hoped that our old space will stand all tests, for, should it not, then all our science would have to be put on a new basis, at least in so far as related to space. So, you see, no one need be discouraged at his inability to perfectly conceive any other space than our common one. But, as the others are logically possible and mathematically true, and are necessary to get a complete knowledge of our own space, we will attempt to convey some notion of them. In our space we have length, breadth, and height, and to each of these corresponds a coördinate in analytic geometry. This is why we call ours a space of three dimensions, and we cannot picture any other dimension. But we find analytic geometry just as ready to deal with a space which should be like ours in every other way, but should have another or fourth dimension; and this led to the question, "May not our space have a fourth dimension?"

Now, our only way of reasoning about the matter is to take analogous cases in the picturable spaces of two dimensions, and carry the analogies up from two to three, from three to four dimensions.

Let us take the easiest illustration. Suppose beings not living on the surface of a sphere, but in the surface of a sphere, and so having no conception of the third dimension of space.

Now, if they were so small as only to perceive a small portion of their surface, they might easily think it a plane, as the ancients thought our earth, and so their geometry would be the same as Euclid's.

But, if they were originally created so large in proportion to their spherical surface as to be immediately affected by its positive curvature, then they would never gather any experience of parallel lines, or of geometrical similarity between figures of different sizes. A straight line being the shortest distance between two points, then all their straight lines or geodesic lines would return upon themselves; and as also any two straightest lines on a sphere must meet somewhere, our imaginary surface men could never learn our theory of parallels and geometry, unless, as has been suggested, they should produce mathematicians sufficiently powerful first to imagine and investigate a surface in which two straight lines might be drawn so as to remain at the same distance apart to infinity; that is, if they could in any way be supposed to have the idea of infinity. Then, as Land says: "Reasoning on this, and a few more suppositions, they might discover the analytical geometry of the plane. Combining this with their original spherical theorems, some genius among them might conceive the bold hypothesis of a third dimension in space, and demonstrate that actual observations are perfectly explained by it. Henceforth there would be a double set of geometrical axioms; one the same as ours, belonging to science, and another resulting from experience in a spherical surface only, belonging to daily life."

In reference to our own science of today, the two analogous questions are:

1. May we not be drawing wrong conclusions about space from our limited experience of space, just as the Greeks concluded that the earth was flat?

2. If our conclusions so far are true, yet may there not be, in addition to the three dimensions we know, still another or fourth dimension in space?

The idea of space of four dimensions has been successfully used by Salmon, Clifford, and Sylvester, in their researches, and Cayley has published "Chapters in the Analytical Geometry of n Dimensions." Spaces of two and three dimensions with constant curvature have been carefully investigated by Beltrami, Helmholtz, and now Frankland. I mention these as among the most important and easily procurable writings on the subject. In reality there have been about a hundred books and memoirs treating of new or non-Euclidean space.

Of that kind of non-Euclidean surface now being discussed in Nature, a very pretty idea may be obtained by likening it to a hemisphere on which, when any moving point has reached the edge, it is supposed, without any jump or any further motion, to have reached the corresponding point on the opposite edge, so that the meridians, great circles, shortest lines, instead of intersecting twice, as they do on the earth, only intersect once and yet return upon themselves. This, like the sphere, is called a surface of positive curvature, in reference to the plane, which has no curvature.

Now, just as to the plane corresponds an uncurved or homaloidal space, so to a surface of positive curvature corresponds a space of positive curvature; and if the space in which we live can be proved to have the slightest positive curvature, it instantly follows that the universe is only finite in extent, and that every physical straight line, for example, every ray of light, if sufficiently produced, returns into itself.

In an article in your March number, upon "The Early Man of North America," the writer says of the Esquimaux, "They are from their speech a branch of the Turanian family, and allied to the Hungarian, Turkish, Lapp, and Basque races." Whitney, in his work on "Life and Growth of Language," says of the Basque: "It stands entirely alone; no kindred having been found for it in any part of the world." He further says: "Attempts have been made to connect them" (the American languages) "with some dialect or family in the Old World, but with obviously unavoidable ill success. . . . There appears to be no tolerable prospect that, even supposing the American languages derived from the Old World, they can ever be proved so, or traced to their parentage." In the same article there is the statement that the Esquimaux "extend in scattered companies for nearly five hundred miles on the coast of Asia beyond Behring's Straits," while other writers assert that the Esquimaux have no kindred on the Eastern Continent.

As the philosopher of the nineteenth century claims that "in his hands theory is never divorced from fact," we who are not philosophers complain, as we have the right to do, when they flatly contradict each other and furnish no evidence to fortify their statements. We accept their dicta so long as they agree, but we object to a dictum which contradicts another dictum equally respectable.⁠D. A. Hulett.

New York,May 12, 1877.

EDIBLE MUSHROOMS.

To the Editor of the Popular Science Monthly.

Sir: In the paper on "Mushrooms," etc., in the last number of your Monthly, I think Mr. Julius A. Palmer, Jr., uses the name of "Dr. Curtis, of South Carolina," for that of the great mycologist, Dr. Moses A. Curtis, of North Carolina, in connection with letters written to Mr. Sprague on "Mushrooms." Whether that is so or not, I am safe in saying that during our late war Dr. Moses A. Curtis wrote a work on "The Edible Fungi of North Carolina," illustrated with colored drawings by his son (I believe the Rev. Charles Curtis), and this manuscript work is still in existence. It is the result of Dr. Curtis's botanical investigations, as well as of his personal experience, as to which of the mushrooms are fit to eat. Many times, I am told, the good doctor had uncomfortable symptoms after trying a new mushroom, but you may be sure he did not stop until he learned more about it. His researches were begun in the war with a view to furnish such information to his people as would enable them to recognize edible mushrooms, and so supplement the poor diet so universal among even the better classes, but I believe he never cared to publish the work. I deem it but justice to the memory of Dr. Curtis to make this statement.⁠Thomas F. Wood.

Wilmington, North Carolina,April 30, 1877.

To the Editor of the Popular Science Monthly.

Sir: Will you permit a suggestion as to Mr. Herbert Spencer's descriptive term "negatively quantitative," and his specifications under it? It appears to me to belong to an undesirable class of definitions, because its defining part consists not only in asserting the absence of something, but in so asserting it as to require just as much the assertion of all the other absences that exist. That is to say, Mr. Spencer's definition, and his explanations of it, as cited in the Monthly of March, page 611, appear to me to necessarily imply the following preliminary proposition (which I do not think Mr. Spencer meant to imply): "A definition may consist of a statement that a single quality or characteristic is excluded from the thing defined." Now, of course, a definition, to be a good one, must accomplish two things, neither of which the above is: it must specify the qualities which the thing defined does possess; and it must exclude—not some one other, but—all others.

Further: is not the term "negatively quantitative" liable to be misunderstood from ambiguity? It seems to me that it may honestly be taken to mean either of the two following:

1. Being such as to exclude dealing with quantity or quantities.

2. Being such as to include, so far as it does deal with quantities, only what are called "negative quantities."

These are, of course, quite different meanings. It appears to me that Mr. Spencer applied the former, and that Mr. Halsted. in his communication to you, had in his mind the latter. If so, a misunderstanding was pretty likely.

I need not explain the benefit of avoiding the use for one purpose of terms already employed for another. And as I am a sincere admirer of Mr. Spencer, and of his great contributions to the advancement of sound thought, I hope you will not suppose I want to do anything in the way of attacking or fault-finding.⁠F. B. P.

Boston,April 8, 1877.

THE HABITAT OF THE GAR-PIKE.

To the Editor of the Popular Science Monthly.

Sir: Since the publication, in the May number, of the first part of my article "Gar Pikes, Old and Young," I have had information as to the occurrence of Lepidosteus in Black Lake, near Ogdensburg, New York; in the Patapsco River, Maryland, and in the Edisto, Ashepoo, and Combahee Rivers, South Carolina.

It being commonly supposed that Lapidosteus is rarely found outside of the Great Lakes or the Mississippi River and its tributaries, I shall be much obliged to your readers for any information as to its occurrence elsewhere. Particularly valuable would be facts as to the time and place of spawning; and the eggs or newly-hatched young are greatly desired.